The invention relates to a separator to remove magnetic particles from liquid phases, consisting of an application unit, a separating unit and a collecting unit. This separator can be used to fractionate biological materials, in particular to remove cells, antigens, antibodies, enzymes etc., with the aid of magnetic microspheres (MIMS).
There has been a considerable increase in recent years in the interest in efficient analytical and preparative cell separation procedures. Since cell biologists have increasingly turned their attention to the investigation of the functional interaction of even the smallest subpopulations of cells within heterogeneous mixtures, the requirements of a separation technique are not only the necessary quantitative physical efficiency but also the ability to make specific qualitative differentiations. Up to the present time, the density centrifugation technique, which separates various cells on the basis of the physical parameters volume and density, has retained its uncontested value for the first requirement mentioned (see Hutchins, D. and C. M. Steel, in: Peters, H. editor: Separation of cells and subcellular elements 1979; A. J. Fluks, 1981, J. Immunol. Methods 41: 225; A. J. Ulmer and Flad H. D., 1984, Immunobiol. 166: 238), but at the expense of limited specificity (selectivity).
The only techniques which can be used for the second requirement are those which, owing to their ability to make use of different molecular surface structures of various cells (target molecules such as antigens, receptors or the like) as separation parameters, carry out biospecific, and thus selective, separations. In this connection, solid-phase affinity techniques, which separate on the basis of serological reactions, should be especially picked out.
These methods allow specific separation of cells or cellular material by differentiation of molecular surface structures, for example antigens, by immobilization of antibodies on plastic surfaces (for example the panning procedure: Wysocki, L. J. and V. L. Sato, 1978, Proc. Nat'l. Acad. Sci. 75: 2844; Basch, R. S. et al., 1983, J. Immunol. Methods 56: 269), glass or gel materials (Basch, R. S. et al., loc. cit.) which can be packed to form columns. The disadvantages of these procedures are non-specific binding reactions with material surfaces, the blockage of columns owing to aggregating particles or cells, adverse effects on sensitive cells owing to shear forces, long process times and, very especially, the lack of capacity to deal with large amounts.
In contrast, in liquid-phase procedures, in which the actual separation process takes place from dilute suspensions, it is possible almost entirely to eliminate nonspecific adhesion, inadequate conservation of cells, and shear forces. The following may be mentioned in this connection: Cell immunoelectrophoresis (van Oss et al., 1979, Immunol. Communic. 8: 419), FACS (Loken, M. R. and A. M. Stall, 1982, J. Immunol. Methods 50: R 85), and magnetic cell separation techniques based on antibody-conjugated magnetic microspheres (MIMS). Common to all these techniques is the combination of the serological specificity of antibodies with a controllable physical force: electric field, optical recognition or magnetic field.
Although, for example, FACS at present represents the state of the art in the field of analysis--despite its high costs of acquisition and maintenance, in particular because of its multifactorial character--it has an important disadvantage, as has also cell immunoelectrophoresis: the capcity available for preparative use is strictly limited and is inadequate to deal with large amount of cells in an acceptable time.
In contrast, the use of magnetic microspheres offers remarkable advantages, since magnetic separation procedures with microspheres are low-cost and straightforward in their process sequence and, in particular, can be used preparatively with acceptable economy not only for dealing with large amounts of cells (10.sup.6 -10.sup.12 cells) but also for the rapid isolation of other cellular particles.
However, in this connection, an additional important system objective must be the parallel development and provision of a favourable priced unit of apparatus, in which the specific separating efficiency of MIMS is exploited, in an industrially reliable and reproducible manner, and the extensive analytical and preparative possibilities are made use of flexibly and quantitatively efficiently. The present invention relates to the provision of a separator of this type.